I'm afraid I don't know the size and type of wiring ran to the oven now. I can tell you that all the wiring is ran from a switched double pole cooker outlet. The new single cooker has a max oven absorptionof 2000 W and a max electric hob absoprtion of 7000 W.
It states in the installation guide that the power supply cable must have minimum requirements as follows:
I don't know whether any of this info helps - sorry.